Dried herbs mixed with stimulant chemicals carefully packaged to dodge drug laws are gaining in popularity among young Japanese, leading in turn to a drastic increase in the shops selling such products.

These “dappo habu” (law-evading herbs) contain stimulant materials whose chemical components are slightly different from those prohibited by drug laws.

The Tokyo Metropolitan Government identified two shops selling such products in fiscal 2009. As of last Friday, 89 such shops were in existence, many of them in Shinjuku and Shibuya, areas popular with young people.

“Even if (herbs) do not include chemicals designated (as illegal) by law, you can’t say they are safe. (Inhaling them) is like conducting a human experiment with your own body,” said Masahiko Funada, who heads a team researching addictive drugs at the National Center of Neurology and Psychiatry in Tokyo.

The Health, Labor and Welfare Ministry has been locked in a race with dealers as it keeps adding new stimulants to its list of illegal drugs while dealers keep marketing new products, including new chemicals they say are not covered by drug regulations.

The ministry recently decided to introduce a new and more comprehensive system for designating illegal drug components.

Even if dappo herbs don’t include illegal chemicals, selling them can be a violation if the seller specifically instructs the buyer how to use the stimulant, such as by inhaling.

Many of the shops, however, are cagey enough to evade the law. They sell the dappo herbs as “incense,” not something to be consumed or inhaled directly.

Police and local governments have recently started cracking down.

In January, two shop managers in Osaka were arrested for alleged possession of illegal drugs for the purpose of marketing them.

On Jan. 25, three teens in Tokyo were hospitalized for acute drug poisoning after inhaling smoke from herbs mixed with chemicals. The shop dealer who sold it to them was arrested on suspicion of inflicting bodily harm.